Rubber track brake

ABSTRACT

The invention relates to a rubber track brake wherein each steel rail is provided with an element having an inclined surface projecting laterally inwardly so that the flange of a vehicle wheel contacts the surface at only a single point close to the foot of the rail, thereby minimizing friction even as the wheel moves up the surface somewhat under the influence of centrifugal force as when going around a curve.

United States Patent Preinfalk et al.

1451 Apr. 18, 1972 1541 RUBBER TRACK BRAKE [72] Inventors: FranzPreinfalk, Langenfeld; Dietmar Ulbricht, Dinslaken; Friedrich Rohrsen,Rodenberg, all of Germany [73] Assignees August Thyssen-HutteAktiengesellschaft,

' Duisburg-Hamborn, Germany [22] Filed: May 19, 1970 [21] App]. No.:38,812 [30] Foreign Application Priority Data May 23, 1969 Germany ..P19 26 358.2

Dec. 9, 1969 Germany ..P 19 61 604.7

[52] U.S.Cl .....l88/62, 238/15 [51] Int. Cl ..B61k 7/02 [58] Field ofSearch ..238/15-1 7; 188/62 [56] References Cited 4 UNITED STATESPATENTS 1,499,743 7/1924 McNamara ..238/17 3,141,526 7/1964 Wynn..188/62 3,311,304 3/1967 Becker.... ..238/17 509,788 11/1893 Baker..238/17 1,726 8/1840 Naglee ...238/15 2,779,441 1/1957 Beltmanetal..l88/62 Primary Examiner-Arthur L. La Point Assistant Exdminer-RichardA. Bertsch Attomey -Burgess, Dinklage & Sprung ABSTRACT The inventionrelates to a rubber track brake wherein each steel rail is provided withan element having an inclined surface projecting laterally inwardly sothat the flange of a vehicle wheel contacts the surface at only a singlepoint close to the foot of the rail, thereby minimizing friction even asthe wheel moves up the surface somewhat under the influence ofcentrifugal force as when going around a curve.

6 Claims, 2 Drawing Figures RUBBER TRACK BRAKE The invention relates toa rubber track brake, especially one to be laid in a curve, having railsof rubber elastic material and steel rails disposed alongside andparallel to the rubber rails,

each steel rail having a virtually horizontal running surface for theflanges of the wheels of a vehicle and an approximately perpendicularguiding rail for the sides of the wheels.

In prior-art track brakes of this kind, the two rails of a track arereplaced over a certain length by rubber rails which form the brakebodies. The rubber tracks are bonded to a support capable of bearing aload. They are adjustable in height between two positions. The oneposition, in which the rubber rails are raised, is the braking position;the other position, in which the rubber rails are lowered, is thefree-running position. When the rubber rails are in the brakingposition, the rolling surfaces or flanges of the wheels of a vehicleroll on the rubber rails. The wheels then sink into the elastic rubberbrake bodies to a greater or lesser depth depending on the weight of thevehicle, whereupon the vehicles energy of movement is partiallytransformed into kneading work. The vehicle is thus retarded when itrolls over the rubber rails. When the vehicle has reached the desiredfinal speed the rubber rails are lowered to the free-running position.In this position the wheels of the vehicle are no longer in contact withthe rubber rails. The flanges of the wheels then roll on the steel railsdisposed alongside the rubber rails. No braking action takes place whenthe rubber rails are in the lowered position.

Both in the braking position and in the free-running position, the caris guided by guiding rails. These are also disposed alongside the rubberrails and form a unit with the rails on which the flanges roll in thefree-running position. The wheels engage the guiding rails as soon asthe motion of the vehicle acquires a transverse component. The guidingrails may not be less than a predetermined height, in order to assurereliable guidance even when a lighter vehicle, i.e., one which does notsink deeply into the rubbery material, passes over the track brake whenthe rubber rails are in the raised position. In track brakes of theprior art, conventional tongue rail sections lie beside the rubberrails, the base of these tongue rail sections forming the runningsurface for the wheel flanges in the freerunning position, while theside surface of the head forms the surface for guiding the sides of thewheels.

When the wheels of a vehicle are forced against the guiding surfaces, asthey unavoidably are by centrifugal force where tracks are laid incurves or in the case of swerving movement of the vehicles, a frictionalforce develops between the guiding surface and the side of the wheel.This friction force is of secondary importance if the rubber rails arein the braking position, in which case it merely adds slightly to thebraking force. The additional friction, however, is extremelyundesirable when the vehicle reaches the required final speed and therubber rails are lowered to the free-running position, because itcreates additional undesired braking and can even cause the vehicle tostop in the brake zone.

The object of the invention is to reduce to a negligible amount theadditional friction caused by the guiding rails in a system asdescribed.

This is achieved according to the invention by the provision on theguiding rail, in a rubber track brake of the kind described hereinabove,of a lateral enlargement facing the wheel of an oncoming vehicle, thesurface of the enlargement tangentially contacting, in the area of theflange, the side of the wheel rolling on the running surface. In apreferred embodiment of the invention, the steel rail consists of aconventional tongue rail section and an additional strip which isinserted into the channel between the rail head and the base of therail, on the side facing the wheel, and whose projecting side surfaceforms the lateral enlargement. It is desirable that the surface of thelateral enlargement, which touches the side of the wheel in the area ofthe wheel flange, be an inclined plane enclosing with the vertical anangle of at least 2 to about 60.

Desirably the inclined plane at its bottom should be rounded so as tomerge smoothly with the substantially horizontal running surface of therail, the radius of curvature of such rounding being greater than theradius of curvature of the wheel flange in cross section. In a preferredembodiment, the inclined plane encloses with the vertical an angle of 5to 12. It is desirable that the upper portion of the lateral surface ofthe guiding strip associated with the wheel be vertical.

The invention will be further described with reference to the drawings,wherein:

FIGS. 1 and 2 show two different embodiments of the invention in crosssection through a rubber braking body with a combination steel raillying beside it and through a wheel that is in the brake.

Referring now more particularly to the drawings in FIG. 1 the rubberbrake body 1 is in the lowered position, out of contact with the wheel 2of the vehicle passing through it. The flange 3 of wheel 2 rolls on theapproximately horizontal surface 4 of the base of a broad-flange rail 5.In contrast to track brakes of the prior art wherein the wheel side 6 isguided against the side surface 7 of the rail head 8, the guidance ishere performed against the lateral surface 9 of an additional strip orelement 10. The strip 10 is fitted into the channel between the railhead 8 and the rail flange 4 of rail 5 and is bolted in place. Thelateral surface 9 has the shape of a steep inclined plane which projectslaterally beyond the vertical plane formed by the lateral surface 7 ofthe rail head 8, toward the wheel 2. Between the lateral surface 9 andthe plane that contains the lateral surface 7 there in included an anglea. In the embodiment, represented, it amounts to about 12. By thisselection of the angle a the surface 9 contacts the wheel 2 urgedagainst it approximately at that point on the wheel flange 3 at whichthe slightly tapering side surface 11 of the wheel flange, whichordinarily forms an angle of 7 with the wheel side 6, merges with thesurface portion 12 of arcuate cross section. In other words, the pointof contact is placed very low. This means that the frictional forcelever arm, from the point of contact to the bearing point 13 of thewheel flange is very short, amounting to only a small fraction of whatthe lever arm would be if the guiding were performed at the lateralsurface 7 of the rail head 8. Accordingly, the undesired braking poweris extraordinarily low.

The lateral surface of the steel rail that serves for the guidance ofthe wheel can, of course, be of a different shapea bolster shape, forexample. In any case the important thing is that the contact take placein the area of the wheel flange so that the lever arm of the frictionalforce will be small. The embodiment shown has the advantage that therail 5 is of a conventional profile and therefore is easy andinexpensive to procure. The additional strip 10 is also easy tomanufacture. When it is worn out, it can easily be removed from the rail5 and replaced.

In the embodiment of FIG. 2 the rubber rail 1a is again in the loweredinactive position out of contact with the wheel 2a of an oncoming car.The flange 3a of wheel 2a rolls on the approximately horizontal surface14 of the base of a steel rail 15. This steel rail is formed from aspecial shape which is made, for example, by planing a billet ofrectangular cross section. It is bolted to an understructure 16, whichconsists of profiled members welded together. The lateral surface ofsteel rail 15 facing wheel 2a has a portion 17 at the top which isvertical and which is adjoined by a steep inclined planar portion 19beneath it, which progressively merges with a rounded portion 18terminating in a horizontal or, better, slightly inclined portion 14.The radius of curvature of the rounded portion 18 is greater than theradius of curvature of the surface of the wheel flange in theimmediately adjacent area identified as 12a.

When a car runs centrally through the brake, the wheel flange 3acontacts rail 15 at only one point in the area of the surface portion14. Now, if one assumes, for example, that rail 15 is the inside rail ina curve, an oncoming vehicle will be urged outward by the centrifugalforce, in the direction of the arrow 20. The point of contact betweenwheel flange 3a and rail 15 will then move upwards along the roundedportion 18, to an extent depending on how far the car is forced outward.

On the corresponding outside rail of the curve, however, the point ofcontact of the other wheel moves downward slightly. In this manner therails exercises a guiding force, although there is only a single pointof contact between each rail and its wheel. The friction is thus veryslight, being practically only rolling friction. Not until thecentrifugal action is relatively strong is the wheel forced against rail15 to such an extent that it contacts it at a second point, namely atthe point of transition between the flat wheel side 6a and the gentlytapering part 11a of the wheel flange surface. But even in this case theadditional, undesirable braking power is slight, since the lever arm ofthe frictional force is small.

Because the point of contact between rail and wheel moves upward on theinside rail of a track curve and downward on the outside rail, theeffective rolling radius of the wheel is reduced on the inside of thecurve and increased on the outside. This compensates, to a great extent,the difference in length between the inside rail and the outside rail.In this manner the slippage between wheel and rail, which occurs inother systems with attendant additional friction and increased wear, isvirtually excluded.

in the area of the upper portion 17, there is no contact in any casebetween the guiding rail and the side of the wheel when the brake bodiesla are lowered. This portion of rail 15 serves only as a guide for thevehicle when the brake bodies are in the raised position. Theillustrated rail with the vertical portion 17 has the advantage over arail in which the inclined plane 19 might be continued all the way tothe top that the guidance of a vehicle during the braking action iscloser and more precise.

As employed herein rubber includes natural and synthetic rubber as wellas rubber-like elastic materials whatever their chemical composition.

It will be appreciated that the instant specification and examples areset forth by way of illustration and not limitation, and that variousmodifications and changes may be made without departing from the spiritand scope of the present invention.

What is claimed is:

- 1. A rubber track brake, adapted for laying in a curve and for usewith a vehicle having flanged wheels, comprising A. a first pair ofparallel rails having a rubber upper surface,

B. a second pair of rails respectively alongside said first pair ofrails, each of said rails of said second pair having a. an approximatelyvertical guiding surface for the side of the vehicle wheel,

b. an approximately horizontal running surface for the flange of thewheel, and

c. a laterally projecting element facing inwardly toward the wheel, thesurface of said element contacting the side of said wheel adjacent itsflange.

2. A track brake according to claim 1, wherein each rail of said secondpair comprises a rail portion having a head and a foot defining achannel there between, and a strip comprising said laterally projectingelement, said strip seating in said channel and projecting laterallyinward of said head.

3. A track brake according to claim 1, wherein the surface of saidelement contacting the side of said wheel adjacent its flange is aninclined plane enclosing with the vertical an angle of at least 2 toabout 60.

4. A track brack according to claim 3, wherein the inclined plane mergessmoothly through a rounded portion with the approximately horizontalrunning surface, the radius of curvature of the rounded portion beinggreater than the radius of curvature of the wheel flange surface incross section.

5. A track brake according to claim 4, wherein the inclined planeencloses with the vertical an angle of 5 to 12.

6. A rubber track brake according to claim 1, wherein the upper portionof the surface of said element contacting said wheel side is vertical.

1. A rubber track brake, adapted for laying in a curve and for use witha vehicle having flanged wheels, comprising A. a first pair of parallelrails having a rubber upper surface, B. a second pair of railsrespectively alongside said first pair of rails, each of said rails ofsaid second pair having a. an approximately vertical guiding surface forthe side of the vehicle wheel, b. an approximately horizontal runningsurface for the flange of the wheel, and c. a laterally projectingelement facing inwardly toward the wheel, the surface of said elementcontacting the side of said wheel adjacent its flange.
 2. A track brakeaccording to claim 1, wherein each rail of said second pair comprises arail portion having a head and a foot defining a channel there between,and a strip comprising said laterally projecting element, said stripseating in said channel and projecting laterally inward of said head. 3.A track brake according to claim 1, wherein the surface of said elementcontacting the side of said wheel adjacent its flange is an inclinedplane enclosing with the vertical an angle of at least 2* to about 60*.4. A track brack according to claim 3, wherein the inclined plane mergessmoothly through a rounded portion with the approximately horizontalrunning surface, the radius of curvature of the rounded portion beinggreater than the radius of curvature of the wheel flange surface incross section.
 5. A track brake according to claim 4, wherein theinclined plane encloses with the vertical an angle of 5* to 12*.
 6. Arubber track brake according to claim 1, wherein the upper portion ofthe surface of said element contacting said wheel side is vertical.